First before I ask I'd like to specify that I have not reached any conclusions and it might be caused by a carrier misconfiguration, weak signal or else. I am curious about figuring out what may be the cause, I see this more as a learning opportunity and as a form of troubleshooting than problem-reporting (at least for now).

I have been getting notifications (beep) every now in then in the same physical location. Without any notification to read. I know that the signal tend to be weak and suspect that I might be roaming, but I have been routinely getting spam call in the past in the same area and disabling 2G reduced that significantly. Looking at statuses and sometimes logs, I can see that my phone carrier has some tower operates in ipv4, while other use ipv6.

Doing some google searches returned post like this one, this one, or that one. Spending the two months reading the nitty-gritty of IMS and all its technical standard would be undesirable as I would likely forget it all shortly thereafter. If this is the only way then so be it. Instead I think it would be a great opportunity to better develop my skills at crunching logs, or getting familiar with tools that can do this efficiently.

I can see in the ImsService logs that the emergency number is being updated, with the proper phone number but with an mcc of null. My limited understanding is that this is happening while it is roaming, and that null mcc might be caused by weak signal or interference for example; not something that I would want to interfere with or disable but I think it can provide some context. Then in the main system logs, I can see a notification_alert with beep=1 which would be the notification I had. Just above that are sysui_multi_cation with a multiple numbers and com.android.phone.

What would be the best way to delve deeper and aim to understand the relationship between the two, is there an easy way to do this (e.g. some database to query) or is cross-matching various logs the way to go? While I might use this as the perfect reason to learn how to use ed and awk, is there any program to recommend that run on linux?

For hardening(-ish), I am wondering what can be customized without potentially causing issues with my phone carrier. It's possible that all my concerns have been quite well addressed and/or mitigated some times ago. Can writing a custom APN prevent some features from being used, or something similar? Any settings that can prevent any roaming tower from overriding settings, if this is even a thing? I'd be ok with missing features while roaming since I am merely in a zone with spotty signals.

If none of that is possible due to the nature of cellular network, any suggestion on how to best monitor IMS?